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* [gcc r14-3352] LCM: Export 2 helpful functions as global for VSETVL PASS use in RISC-V backend
@ 2023-08-21 9:29 Lehua Ding
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From: Lehua Ding @ 2023-08-21 9:29 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:d5dfba19aee783a6ba90fdba1993d576c7ec310b
commit r14-3352-gd5dfba19aee783a6ba90fdba1993d576c7ec310b
Author: Juzhe-Zhong <juzhe.zhong@rivai.ai>
Date: Mon Aug 21 09:04:53 2023 +0800
LCM: Export 2 helpful functions as global for VSETVL PASS use in RISC-V backend
This patch exports 'compute_antinout_edge' and 'compute_earliest' as global scope
which is going to be used in VSETVL PASS of RISC-V backend.
The demand fusion is the fusion of VSETVL information to emit VSETVL which dominate and pre-config for most
of the RVV instructions in order to elide redundant VSETVLs.
For exmaple:
for
for
for
if (cond}
VSETVL demand 1: SEW/LMUL = 16 and TU policy
else
VSETVL demand 2: SEW = 32
VSETVL pass should be able to fuse demand 1 and demand 2 into new demand: SEW = 32, LMUL = M2, TU policy.
Then emit such VSETVL at the outmost of the for loop to get the most optimal codegen and run-time execution.
Currenty the VSETVL PASS Phase 3 (demand fusion) is really messy and un-reliable as well as un-maintainable.
And, I recently read dragon book and morgan's book again, I found there "earliest" can allow us to do the
demand fusion in a very reliable and optimal way.
So, this patch exports these 2 functions which are very helpful for VSETVL pass.
gcc/ChangeLog:
* lcm.cc (compute_antinout_edge): Export as global use.
(compute_earliest): Ditto.
(compute_rev_insert_delete): Ditto.
* lcm.h (compute_antinout_edge): Ditto.
(compute_earliest): Ditto.
Diff:
---
gcc/lcm.cc | 7 ++-----
gcc/lcm.h | 3 +++
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/gcc/lcm.cc b/gcc/lcm.cc
index 94a3ed43aeab..03421e490e46 100644
--- a/gcc/lcm.cc
+++ b/gcc/lcm.cc
@@ -56,9 +56,6 @@ along with GCC; see the file COPYING3. If not see
#include "lcm.h"
/* Edge based LCM routines. */
-static void compute_antinout_edge (sbitmap *, sbitmap *, sbitmap *, sbitmap *);
-static void compute_earliest (struct edge_list *, int, sbitmap *, sbitmap *,
- sbitmap *, sbitmap *, sbitmap *);
static void compute_laterin (struct edge_list *, sbitmap *, sbitmap *,
sbitmap *, sbitmap *);
static void compute_insert_delete (struct edge_list *edge_list, sbitmap *,
@@ -79,7 +76,7 @@ static void compute_rev_insert_delete (struct edge_list *edge_list, sbitmap *,
This is done based on the flow graph, and not on the pred-succ lists.
Other than that, its pretty much identical to compute_antinout. */
-static void
+void
compute_antinout_edge (sbitmap *antloc, sbitmap *transp, sbitmap *antin,
sbitmap *antout)
{
@@ -170,7 +167,7 @@ compute_antinout_edge (sbitmap *antloc, sbitmap *transp, sbitmap *antin,
/* Compute the earliest vector for edge based lcm. */
-static void
+void
compute_earliest (struct edge_list *edge_list, int n_exprs, sbitmap *antin,
sbitmap *antout, sbitmap *avout, sbitmap *kill,
sbitmap *earliest)
diff --git a/gcc/lcm.h b/gcc/lcm.h
index e08339352e03..7145d6fc46df 100644
--- a/gcc/lcm.h
+++ b/gcc/lcm.h
@@ -31,4 +31,7 @@ extern struct edge_list *pre_edge_rev_lcm (int, sbitmap *,
sbitmap *, sbitmap *,
sbitmap *, sbitmap **,
sbitmap **);
+extern void compute_antinout_edge (sbitmap *, sbitmap *, sbitmap *, sbitmap *);
+extern void compute_earliest (struct edge_list *, int, sbitmap *, sbitmap *,
+ sbitmap *, sbitmap *, sbitmap *);
#endif /* GCC_LCM_H */
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